7. Purchase a Gym Membership

Getty Images

The surest way to get a slimmer girlfriend is to get yourself off the couch. Join a gym together. Or encourage her to join yours. Or recommit to the gym membership you already have. There’s a reason people dry out together, train for marathons together, and go on Mormon missions together. It’s this: it’s harder to quit on something when someone else is relying on you to show up. “Baby, let’s get in shape,” is how you introduce this topic. Do it together, even if you have totally separate routines once you’re there. Bonus activity: post-gym shower sex.